Oxid of thioindigo dyes.



UNITED STATES PATENT OFFICE.

BENNO HOMOLKA, OF FRANKFOET-ON-THE-MAIN, GERMANY, ASSIGNOR TO FARBWERKEVORM. MEISTER LUOIUS & BRUNING, OF HOGHST-QN-TI-IE'-\IAIN, GERMANY, ACORPORA- TION OF GERMANY.

T 0 all whom it may concern:

Be it known that I, BENNo HoMoLxA, Ph. 1)., citizen of the Empire ofGermany, and residing at Frankfort-on-the-Ilain, in the Empire ofGermany, have invented certain new and useful Improvements in theManufacture of Oxids of the Thioindigo Dyestuffs, of Which the followingis a specification.

This invention relates to a new class of technically useful productswhich are related to thio-indigo but contain more oxygen which productsI have discovered and call thio-indigo oxids.

One method of obtaining these new products is by the action of oxidizingagents on thio-indigo dyestuffs; .the latter appear to absorb one atomicproportionof oxygen.

When using the simplest body of thioindigo the reaction occurs accordingto the following equation:

C II O S O U I-L0 8,

thio-iudigo thio-indigo oxid.

As oxidizing agents well-known powerful inorganic agents may be used,particularly suitable being nitric acid and chromic acid, of which theformer generally acts already at ordinary temperature and the latteronly when heated.

Example I: 10-parts by weight of thioindigo are gradually introducedwhile stirring into 100150 parts by weight of cold concentrated nitricacid. After 24-48 hours, the mixture is diluted with water, thethioindigo oxid collected on a filter, washed and dried.

Example II: parts by weight of thioindigo paste of v 20 per cent.strength are digested for some time, say for about 10 to 12 hours, onthe water bath with a solution of 30 parts by weight of sodiumbichromate in 150 parts by weight of water and 45 parts by weight ofsulfuric acid of 66 Be. specific gravity. The thio-indigo oxid thusformed is collected on filters and then'washed and dried.

The thio-indigo oxid is a red, crystalline powder, insoluble in water,also insoluble or almost insoluble in the usual organic solvents but itis soluble to a great extent with a red Specification of Letters Patent.

Application filed May 6, 1908.

OXID OF TI-IIOINDIGO DYES.

Patented Sept. 15, 1908.

Serial No. 431,189.

color in boiling chloroform and boiling xylene. On cooling, thesesolutions yield beautiful red crystals. In concentrated sulfuric acidthe thio-indigo oxid is readily soluble with a rcddishviolet color. Inanalogous manner other bodies of this group may be treated, for instancehomologous or substituted thioindigo dyestuffs, for instance thosecontaining Cl, Br, (OCH or (SO,I-I

The thio-indigo oxids generally dissolve, when heated, both in dilutecaustic soda lyes and in aqueous solutions of the neutral sulfites ofalkalies or alkaline earths. The latter solutions, heated with dilutemineral acids, yield red precipitates Which can also.

be produced in this way on the textile fiber. For this purpose thetissue maybe impregnated or printed with a solution of, forinstance,thio-indigo oxid or dimethoxythioindigo oxid in a solution of sodiumsulfite,

and then dried and passed through Warm diluted hydrochloric acid. Thusfast red dyes are obtained.

Alkaline reducing agents dissolve the thioindigo oxids, thus formingvats which can be used in the usual manner for dyeing.

.I-Iaving now described my invention, What I claim is:

1. The process for the manufacture of oxids of the thio-indigo dyestuffswhich consists in treating the thio-indigo dyestuffs with oxidizingagents.

2. As a new product the oxid obtainable by oxidation of a thio-indigodyestuff, being a red crystalline powder, insoluble in water, ether andligroin, soluble with a red color in boiling chloroform and xylene, alsosoluble with a reddish-violet color in concentrated sulfuric acid,dissolving with an orangeyellow color in dilute caustic soda-lyes and inaqueous solutions of the neutral sulfites, which latter solution yields,when heated,

with dilute mineral acids a red precipitate.-

In testimony whereof, I aflix my signature in presence of two wltnesses.

BENNO HOMOLKA.

IVitnesses:

JEAN GRUND, CARL GRUND.

